Method of fabricating drill pipe



July 13, 1965 R. c. HELDENBRAND 3,193,918

METHOD OF FABRICATING DRILL PIPE Filed Jan. 8, 1962 2 Sheets-Sheet 1 I 22 32 I I 94 -22 1N VENTOR. 20555 6. HL aeA/epAA/a ATTORNEYS Ti Et-S Fl 53-10 July 13, 1965 R. c. HELDENBRAND 3, 3, 8

METHOD OF FABRICATING DRILL PIPE Filed Jan. 8, 1962 2 Sheets-Sheet 2 INVENTOR. Qusseu CL HELDE-NfiPA/VD United States Patent 3,1?3318 METHGD 0F FABRKCATENG DRlLlZ FEE Russell C. Heldenhrand, Box 173, New Iberia, La. Filed Jan. 8, 1962, Ser. No. 164,810 4 Claims. (Cl. 29-447) The present invention relates to earth boring and more particularly, but not by way of limitation, relates to a method for attaching apparatus to a joint of drill pipe.

As is well know in the petroleum industry, during the course of drilling a well by rotary methods, the exterior surface of the rotating drill string is subjected to extensive abrasive wear as a result of rubbing contact with the rock and other geological formations through which the well bore is being drilled. Normal wear of the external surface of the drill pipe can greatly reduce the tensile strength of the drill pipe in a relatively short period of time. During directional drilling, or when drilling through a highly abrasive formation, the rate of surface wear is greatly accelerated. For example, standard four and one-half inch outside diameter drill pipe has a wall thickness of three-eighths of an inch. Consequently, abrasive erosion of only one-eighth inch of the total outside diameter results in a reduction of the wall thickness by one-sixteenth of an inch, which is a reduction of almost seventeen percent. The slightest weakening of the drill pipe due to wear of the exterior surface can be critical in the very deep wells, for example, over ten thousand feet, where tremendous loads must be borne by each of the uppermost joints of the drill string. Should one of the upper joints of the string fail, the entire drill string would be lost in the hole, which usually results in a total loss of both the drill string and the hole. Another well accepted theory of drill pipe failure is predicated on metal fatigue, crystallization or hardening due to repetitive flexing and vibration over a period of time. Generally speaking, the greater the magnitude of flexing and vibration the more rapid the deterioration of the strength of the material. Any extent to which the flexing can be reduced and the vibrations dampened will substantially prolong the life of the drill pipe.

The standard drill pipe joint is approximately thirty feet long and has upset tool joints at either end, one end having a female threaded coupling known as the box, and the other end having a male threaded coupling known as the pin. The upset tool joints for standard four and one-half inch 0.13. drill pipe are approximately six inches O.D. It has long been known that drill pipe will usually fail or be pulled apart somewhere in the middle of a joint when abrasive wear or metal fatigue is the cause of failure. This is due to the fact that maximum abrasive wear of the small diameter or center portion of the pipe joint, as well as the maximum fiexure and vibration of the drill string, occurs substantially at the midpoint of each pipe joint.

In an attempt to reduce both the external Wear and the excessive flexure and vibration of the drill pipe joints, many attempts have heretofore been made in the art to provide some type of protector or spacer for attachment to the midpoint of the joints of drill pipe in an effort to prevent the relatively thin walls of the drill pipe from contacting the abrasive walls of the well bore, and also to reduce the fiexure and vibration of the joint. These attempts have been greatly frustrated and almost totally unsuccessful because of the somewhat unique construction of a joint of drill pipe. The midpoint protectors cannot be welded to the walls of the pipe because the slightest melting of the metal, even over a relatively minute spot, will destroy the temper and upset the metallurgical balance of the steel and so weaken the pipe joint as to cause eminent failure. Similarly, relatively slight 3,193,918 Patented July 13, 1965 scratches or lacerations of the surface, when circumferentially aligned, will promote cracks to such an extent be prohibitively costly, the only means by which the protectors are made integral with the pipe joint which would be prohibively costly, the only means by which the protector can be attached is by friction. The upset tool joints at either end of the pipe further complicates the problem because any rigid structure to be attached to the center section of each joint must be in the nature of a clamp, many of which have been devised. However, after slight usage, the bolts, pins, or other fastening means for attaching the clamps frequently become loosened and sometimes are even lost in the hole which of course greatly complicates further drilling operations. Integral rubber sleeves have been utilized and are satisfactory in some cases, but even these are frequently lost in the hole. Further, sometimes gas pressure and other forces so displace the rubber sleeves that they become relatively ineffective.

Another relatively frequent cause of drill pipe failure is a result of the relatively sharp teeth of the slips used to secure the drill string at the drilling rig rotary table when the uppermost joint is being connected or disconnected from the string. In very deep wells, the great loads of the drill string causes the slip teeth to dig relatively deeply into the walls of the pipe joint. Since each pipe joint is almost always gripped by the slip teeth about three feet from the box, after repeated use there is a very real likelihood that the series of teeth marks will be circumferentially arranged in such a manner as to cause cracks and ultimate failure of the joint. The use of slips'with teeth has previously been eliminated by providing an auxiliary elevator or slip shoulder at a point about three feet from the box of each joint. However, heretofore such a structure could be successfully manufactured only by machining the last few feet of the drill pipe joint, or by welding a sub having the auxiliary shoulder together with the box onto the end of the drill pipe joint. In either case, the resulting drill pipe joint is very expensive.

Therefore, it is contemplated by the present invention to provide a novel method for applying the protective device to a joint of drill pipe.

Generally speaking, this invention contemplates a novel method for attaching the sleeve around the center section of the drill pipe joint may be summarized as heating the two sleeve halves, clamping the two sleeve halves tightly on opposite sides of the pipe joint, welding the adjacent edges of the halves together, and slowly cooling the welded halves so as not to establish undesirable internal stresses in the metal of the pipe joint.

A very important object of the present invention is to provide a method for heat-shrinking an integral sleeve around a center portion of a joint of drill pipe to securely fasten the sleeve against longitudinal slippage by suflicient frictional force as to support the drill string.

Many additional objects and advantages of the present invention will be evident to those skilled in the art from the following detailed description and referenced drawings forming a part thereof.

In the drawings:

FIG. 1 is an enlarged view of an improved sleeve device in accordance with the present invention partially in section to better illustrate details of construction, and showing a welded seam partially broken away in order to better illustrate the details of the welded seam.

FIG. 2 is a view of the inside of one half of the sleeve device of FIG. 1.

FIG. 3 is an end view of the half of the sleeve device shown in FIG. 1.

FIG. 4 is an enlarged cross sectional view of a welded longitudinal seam of the device of FIG. 1.

.struction.

.as illustrated by the arrow 40 in FIG. 3.

FIG. is a cross sectional view of an alternative seam construction for a sleeve device like that shown in FIG. 1. FIG. 6 is a somewhat schematic cross sectional view through a joint of drill pipe showing the sleeve apparatus for application to the pipe and apparatus for performing the method of the present invention.

FIG. 9 is a side view of an article of manufacture in accordance with the present invention.

FIG. 10 is a side View of another article of manufacture in accordance with the present invention including a schethe adjacent edges of the sleeve halves when both the sleeve halves 12 and 14 are positioned on opposite sides of the pipe 11. An asbestos rope 43, or other heat re- 2 sistant flexible sealing material may be placed in the botmatic cross sectional view of drilling apparatus to illustrate the use of the article.

Referring now to the drawings, a tubular sleeve device indicated, generally by the reference numeral 10 (see FIG.

l) is shown disposed around the center portion of a joint of drill pipe 11. The tubular sleeve device 10 is comprised generally of two sleeve halves 12 and14, each of generally semicircular cross section. The sleeve halves 12 and 14 are disposed on opposite sides of the pipe 11 and the adjacent edges of the sleeve halves are interconnected at two longitudinally extending weld seams indicated 1 generally by the reference numeral 16 (see FIG. 6). The weld seam 16 shown in FIG. .1 is partially broken away to show details of construction. The two sleeve halves 12 and 14 are preferably of identical construction to reduce the cost of manufacture and provide interchangeability. Therefore, for convenience of illustration, only the sleeve half 12 will be described in detail, it being understood that thesleeve half 14 is ofduplicate con- The internal surface 18 (see FIG. 2) of the sleeve half 12 preferably has an internal radius of curvature 20 slightly less than the external radius of curvature of the center section of a new joint of standard drill pipe. The sleeve half 12 may then be applied to either new or worn drill pipe because the sleeve half can be forced onto the slightly larger new drill pipe, or may be'compressed onto the smaller diameter of worn pipe as hereafter described. The sleeve half 12 may be of anydesired thickness, but normally will have a thickness corresponding to that of the upset of the tool joints at the ends of the particular joint of drill pipe. The internal face 18 of the sleeve half 12 is preferably provided with a plurality of randomly arranged projections 22. The projections 22 may take any desired form, depending to some degree upon whether the sleeve halves are molded or machined, but should not be circumferentially aligned and should not be appreciably greater than one-thirty-second of an inch, for example, in height above the face 18. Otherwise, the projections may materially weaken the pipe when pressed into the surface thereof as hereafter de scribed in greater detail. The tip ends 24 and 26 of the sleeve half 12 are preferably at least one-eighth to threesixteenths of an inch in thickness to prevent a'weld, applied as hereafter described, from burning through the sleeve and melting the drill pipe. The interior annular corners 28 and 30 are preferably either beveled or rounded as shown to prevent the sharp edges of the sleeve from digging into and dangerously crimping the pipe when the halves are clamped on the pipe with great force as hereafter described. The ends of the exterior surfaces of the sleeve half 12 is preferably provided with a standard 18 taper to form tapered shoulders 32 and 34. The longitudinally extending edges 36 and 38 of the. sleeve half 12 are preferably slightly tapered from a radius line This construction results in a V-shaped weld groove, indicated generally by the reference numeral 42 (see FIG. 6), between pipe as hereafter described in greater detail.

tom of the weld groove 42 to protect the pipe 11 from the arc and heat of weld material deposited in the groove.

An' alternative weld groove structure is indicated generally by the reference numeral 44 and is illustrated in FIG. 5. A pair of sleeve halves 46 and 4-8 may be identical in construction to the sleeve halves 12 and 14 except for the longitudinally'extendingedges thereof.

The sleeve half 46 is provided with a tapered edge portion 50 and a right angle lip portion 52. The adjacent edge of the sleeve half 48 is provided with a tapered portion 54 similar, but opposite to the tapered portion 50, and also with a groove portion 56 for receiving the lip portion 52. The lip portion 52 and groove portion 56 are dimensioned to provide a close ship-lap fit 'toprevent molten weld material from passing therebetween and contacting the drill pipe 11. The lip portion 52 is preferably from one-eighth to three-sixteenth inches in thickness to prevent an arc Weld from burning therethrough and damaging the pipe 11. The end of the sleeve half 46 not shown is preferably provided with an edge identical to the edge of half 48 which is shown and sleeve halves 46'and 48 may then be of identical construction.

As previously mentioned, when sleeve halves 12 and 14, or the sleeve halves 46 and 48, as the case may be,

'are placed on opposite sides-of the joint of pipell, the

adjacent edges will form longitudinally extending weld grooves 42or 44, respectively. It is desirable that the Weld grooves 42 and 44 have a minimum width at the bottom of the groove, which is that portion of the groove adjacent the pipe 11, in order to assist in striking an arc and to reduce the quantity of weld material required.

When it is known that the'sleeve halves 12 and 14, for

example, are to be used only on new drill pipe, the circumferential Width of the sleeves may be made sufficiently great that the inner corners 60 and 62, as seen in FIG. 4, are almost in abutting relationship when the sleeve halves 12 and 14 are pressed tightly around the However, it will frequently be desirable to secure the sleeve device 10 to used drill pipe the outside ofwhich may be worn down as much as one-eighthinch for example' However, there is clearly a limit as to the amount of 0D. wear which must be compensated for because once drill pipe has worn much beyond one-eighth inch it must be are to be used on both new and used pipe, the circumferential width of the sleeve halves should be such as to compensate for both theO.D. wear of used pipe and also the compression of the pipe so that it will be assured that the adjacent corners 60 and 62 never abut. There- 7 fore, in order to design sleeve halves 12 and 14 which will be applied to either new pipe .or used pipe, the spacing between the corners 60 and 62 when applied to new or'full diameter drill pipe should be on the order of five-thirty-seconds of an inch, although it may be necessary in some instances to design sleeve halves 12 and 14 in at least two sizes wherein one size will be used on new pipe and one size-on pipe having a worn outer diameter. V

The same considerations are relevant when selecting the dimensions of the sleeve halves 46 and 48 of FIG.

5 in order to establish the desired spacing between the end of the lip portion 52 and theadjacent shoulder of the groove portion 56 and also between thelower ends of the tapered portions 50 and 54 which form the weld groove. However, it should be noted that if a gap df five-.thirty-seconds of an inch is to be provided when in the uncompressed state, the lip 52 should at least begin to fit into the groove 56 when the halves 46 and 48 are placed on new pipe before compression. Then when the sleeve halves 46 and 48 are clamped onto the pipe with sufiicient force to compress the pipe one-thirty-second of an inch, the lip 52 will enter the groove 56 sufiiciently to form a seal for preventing molten weld material from contacting the pipe 11. A series of weld beads can then be deposited in the longitudinally extending weld groove 44 to form an integral sleeve from the sleeve halves 4'6 and 48 as hereafter described with greater particularity.

When practicing the method of the present invention to apply the sleeve device to the center portion of a drill pipe joint 11, the pipe joint 11 is first thoroughly cleaned by shot blasting, sand blasting, or any other suitable cleaning method. Next, a relatively thin, uniform coat of sealing material is applied to the cleaned surface of the pipe. The sealing material is preferably a metallic base liquid which will dry quickly, will withstand substantial heat without deleterious effects, and when cured will not adversely affect frictional bonding between the sleeve device 10 and the pipe 11.

Next, the sleeve halves 12 and 14, for example, are preheated to approximately 600 F. The precise temperature is not critical, but the sleeve halves should be heated sufficiently to gain as much thermal expansion as possible without adversely affecting the strength of the metal of both the sleeve halves and the pipe. As a practical matter, steel does not expand appreciably after 600 F. and additional heating may have a deleterious effect upon the strength of the metals.

The sleeve halves are then placed on opposite sides of the pipe joint 11 while still hot at the spot where the pipe has been cleaned and coated, substantially as shown in FIG. 6. The sleeve halves are then clamped firmly against the pipe 11 by suitable dies 68 and 70 which are actuated by hydraulic motors 72 and 74. The dies 68 and 70 are substantially coextensive with the sleeve halves 12 and 14, respectively, and have internal configurations complementing the external configurations of the respective sleeve halves so as to apply a uniform pressure over the entire areas of the sleeve halves. The hydraulic motors 72 and 74 clamp the sleeve halves 12 and 14 around the pipe 11 with a force sufiicient to press the projections 22 into the pipe and also to compress the pipe 11 as much as possible without permanently and adversely affecting the crystalline alignment and strength of the steel of the pipe. It has been found that standard four and one-half inch O.D. pipe may be compressed as much as one-thirty-second of an inch without adverse effects. However, care should be taken not to excessively deform the pipe 11 as otherwise the elastic limit of the material may be exceeded or other undesirable permanent stresses created which would weaken the pipe.

The asbestos rope 43, or other suitable heat resistant packing material may then be placed in the bottom of the weld groove 42 formed by the adjacent edges of the sleeve halves 12 and 14. The uppermost weld grove 42 (see FIG. 6) is then filled with weld material, preferably by an automatic arc welding head represented by the tip 82. The asbestos rope 43 will protect the pipe 11 from the welding arc and from the heat of the molten weld material as it is deposited so that the surface of the pipe 11 will not be excessively heated. The method as heretofore described can easily be performed with sufficient rapidity that the sleeve halves 12 and 14 will not cool significantly below 600 F. before the start of the Welding operation. The heat generated by welding the two sleeve halves 12 and 14 together will readily maintain the sleeve halves at a sufficiently high temperature to insure considerable expansion of the sleeve halves so that when subsequently cooled, the integrally welded sleeve halves will contract and grip the pipe. The first weld groove 42 (the top weld groove in H6. 6) which is filled with weld material may be either partially or completely filled with weld material before the other or lower weld groove 42 is filled, depending upon the apparatus being employed to apply the sleeve device 10 and the degree to which the temperature of the sleeve halves can be maintained uniform during the initial welding operation. In some instances it may be desirable, in order to maintain a more uniform heating of the sleeve halves 12 and 14, and to apply a more uniform clamping pressure, to use a work manipulating apparatus in which the hydraulic motors 72 and 74 are rotatable through 180 without releasing the pressure on the sleeve halves and pipe. When this type apparatus is employed, the pipe can be rotated after only a few weld passes have been made in the first weld groove 42, and then a few weld passes applied to the other weld groove 42. The clamping mechanism can then be manipulated back and forth until both of the weld grooves are completely filled with weld material and thereby maintain a uniform heating and a uniform pressure until the weld is completed.

As an alternative, when only the pipe can be rotated and not the clamping cylinders 72 and 74, the first weld groove 42 which is initially on top can first be partially filled with weld material and the pressure exerted by the hydraulic motors 72 and 74 released so that the pipe 11 can be rotated 180 and the other weld, groove positioned on top so that the weld groove may be filled with weld material. In such a case, the partially completed welded seam will secure the sleeve halves 12 and 14 in position as the pipe and therefore the sleeve halves are rotated, and when the other weld groove42 is positioned on top, the hydraulic motors 72 and '74 are again pressured to apply sufiicient force to clamp the sleeve halves 12 and 14 back in position and compress the pipe as previously described. The second weld groove 42 is then completely filled with weld material. Since the sleeve halves 12 and 14 are still heated to approximately 600 B, when the dies 68 and 70 are unclamped the first, or partially completed weld, will be called upon only to withstand the force of expansion of the pipe joint 11. Then the pipe may be rotated back through 180 and the initial weld completed.

It will readily be appreciated that in the event welding machines or other means are available which are capable of welding in the grooves 42 if positioned in horizontally opposed relationship, the problems of rotating the pipe between welds would be eliminated since both side welds could be made at the same time.

After the two welded seams 16 have been completed to form an integral sleeve and the dies 68 and 70 have been unclamped to release the pressure on the sleeve device 10, the integral sleeve is then slowly cooled to prevent un desirable stresses from being set up in the materials which are sometimes formed by rapid cooling. Slow cooling of the sleeve may be accomplished by any suitable means, such as an insulated jacket 86 shown in FIG. 8 which may be buckled around the pipe 11 and the sleeve device 10. The jacket should be ventilated to prevent condensation and collection of moisture which might result in uneven cooling of the sleeve 10 and of the pipe 11.

It is to be understood that the sleeve halves 46 and 48 may be applied to a joint of drill pipe in exactly the same manner as the sleeve halves 12 and 14, except that the ship-lap seal formed by the lip 52 and groove 56 eliminate the need for placing the asbestos rope 43 in the weld groove 42 to protect the drill pipe 11 from the molten weld material.

When the pressure of the clamping dies is released and the integral sleeve cooled, it will be evident that the combined forces created by the expansion of the pipe joint and the thermal contraction of the integral sleeve will result in an extremely tight fit between the sleeve device 10 and the drill pipe. The small projections 22 will have been forced into the walls of the pipe 11 both by the pressure of the dies 68 and 70 and ultimately by the heat+ shrinking of the integral sleeve to materially assist in holding the sleeve device 10 against longitudinal slippage along the pipe. The metallic'sealing coating which was applied to the pipe does not materially serve as a bonding agent, but is included primarily-to make theijoint between the sleeve device 10 and the'pipe. moisture proof to prevent corrosion. The rounded or otherwise beveled annular corners 28 and 30 at the ends of the sleeve prevent a short radius crimp of the surface of the pipe 11 as the sleeve device is forced into and subsequently squeezes the pipe. The thickness at the ends 24 and 26 together with the asbestos rope 43, or the lip 52, as the case may be, prevented any molten weld materials from contacting the exterior wall of the pipe 11. The exterior shoulders 32 and 34 are preferably of identical standard 18 taper, which is that taper used on the box and pin upset shoulders. The sleeve halves are identical to reduce the cost of manufacture and provide interchangeability of the two halves 12 and 14. The upper tapered shoulder reduces the likelihood that the tubular sleeve device 10will hang up on irregularities'in the hole.. The lower shoulder 34 provides an auxiliary elevator or plain slip shoulder so that conventional toothedslips will not be required to hold the pipe.

The resulting article of manufacture is shown in FIGS.

- 9 and 10 wherein an improved drill pipe joint 90 is 98. The plain slips 98 are disposed in a master bushing 99 which is turn is supportedby the drilling rig floor.

structure 100 in the conventional manner. The sleeve device 10 when pressure fitted and heat-shrunk onto the drill pipe 94 by the novel method herein described will frictionally grip the pipe with such tenacity as to support loads substantially as great as the joint of pipe 94 is capable of supporting. eliminates the necessity of using slips having teeth and thereby eliminates'marring of the surface of the drill pipe during use by slip teeth.

From the above detailed description it will be evident that a novel and highly useful device for attachment to a tubular article has been described together with a novel method for applying the device in such a manner as to produce a novel article of manufacture. However, having thus described the preferred embodiments of this invention, it is to be understood that various changes, alterations and substitutions can be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

What is claimed is: I

1. A method for applying a protective sleeve device to the center portion of a'jointof drill pipe havingup'set coupling means at each end thereof comprising the steps of:

heating a split sleeve;

holding the sleeve tightly around the I center portion i and protecting the drill pipe from excessive heat z caused by the We d; an

The auxiliary shoulder 96 cooling the integrally formed sleeve whereby the sleeve will contract and tightly grip the pipe.

2. A method for applying a protective sleeve device to the center portion of a joint of drill pipe comprising the steps of:

, heating, two sleeve cross section; clampingthe two sleeve halves tightly on opposite sides of the center portion of the drill pipe; welding the adjacent edges of the two sleeve halves togetherto form an integral sleeve around the center portion of the drill pipe; and,

cooling the sleeve whereby the circumferenceof the sleeve will decrease and tightly grip the drill pipe to prevent longitudinal slippage of the sleeve therealong. I l

3.. A method for applying a protectivesleeve device to the center portion of a-joi'nt of drill pipe comprising halves of generally semicircular the steps of: I r

heating two sleeve halves of generally semicircular cross section; V clamping the two sleeve halves tightly on opposite sides of the center portion of the drill pipe with the edges of the sleeve halvesin adjacent relationship to form two generally'V-shaped weld grooves; "placing a heat resistant insulating material in thebottom of the V-shaped weld grooves adjacent the center portion to protect'the drill pipe from the heat of Welding; welding the adjacent edges of the sleeve halves to form. an integral sleeve around the center portion;

and, p slowly cooling the sleeve whereby the circumference of the sleeve will decrease and the sleeve will tightly grip the drill pipe to prevent longitudinal slippage of the sleeve therealong. 4. A method for applying aprotective sleeve device to the center portionof a joint of drill pipe comprising thesteps of z" i i heating two sleeve halves of generally semi-circular cross section;

clamping the two sleeve halves tightly on opposite sides of the center portion of the drill pipewith sufficient force to compress the drill pipe without exceeding the elastic limit thereof; welding the adjacent edges of the two sleeve halves together to form an integral sleeve aroundfthe center portion of thedrill pipe; and, slowly cooling the sleeve whereby the. combined forces caused by the expansion of the drill pipe when the sleeve halves. are unclamped and the contraction of the integral sleeve due to cooling will cause the sleeve to tightly grip the drill pipe against longitudinal slippage. V 1

References Cited by the Examiner UNITED STATES PATENTS 1,265,706 5/18 Bardeen 29-447 X 2,197,883 4/40 Sinclair 29149.5 2,259,023 10/41 :Clark.

2,267,339 12/49 Paulsen 29-447 2,761,205 9/56 Sikolsi 29447 2,821,010 1/58 Vasconi 29l 49.5

2,877,062 3/59 Hall et a1. 3084 3,051,532 8/62 Collett 308-4 WHITMORE A. WILTZ, Primary Examiner.

MILTON KAUFMAN, ROBERT C. RIORDON,

Examiners.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3,193,918 July 13, 1965 Russell CL Heldenbrand It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 10, for "know" read known column 2, lines 3 and 4, strike out "be prohibitively costly, the only means by which the protectors are made integral with the pipe joint which would and insert instead as to be highly dangerousv Therefore, unless the protectors are made integral with the pipe joint which would column 5, line 1, for "df" read of column 5, line 60, for "grove" read groove column 7, line 38, for "is", first occurrence, read in Signed and sealed this 21st day of December 1965.

SEAL) Ittest:

RNEST W. SWIDER EDWARD J. BRENNER ttesting Officer Commissioner of Patents 

1. A METHOD FOR APPLYING A PROTECTIVE SLEEVE DEVICE TO THE CENTER PORTION OF A JOINT OF DRILL PIPE HAVING UPSET COUPLING MEANS AT EACH END THEREOF COMPRISING THE STEPS OF: HEATING A SPLIT SLEEVE; HOLDING THE SLEEVE TIGHTLY AROUND THE CENTER PORTION OF THE DRILL PIPE; WELDING THE SPLIT SLEEVE TO FORM AN INTEGRAL SLEEVE WHILE HOLDING THE SLEEVE TIGHTLY AROUND THE DRILL PIPE AND PROTECTING THE DRILL PIPE FROM EXCESSIVE HEAT CAUSED BY THE WELD; AND, COOLING THE INTEGRALLY FORMED SLEEVE WHEREBY THE SLEEVE WILL CONTRACT AND TIGHTLY GRIP THE PIPE. 